Sony PCV-R553DS - Manual (Page 107)

Miscellaneous Technical Information 93
Beep Code Error Messages
During a normal bootup, a single short beep signifies that the system is
OK. Other beep patterns signify errors. The number of beeps indicates the
specific error that occurred.
The Sony Online Support technical representative will need to know how
many beeps your system produces if there is an error, so be sure to count
the number of beeps before calling for support.